Field of the Invention
The present invention relates to an image sensor.
Discussion of the Related Art
An image sensor is a semiconductor device that converts an optical image into an electrical signal. A charge coupled device (CCD) image sensor and a complementary metal oxide semiconductor (CMOS) image sensor are representative image sensors.
In general, the CMOS image sensor may be divided into a 3T type, a 4T type, or a 5T type image sensor according to the number of transistors. The number of transistors in the type constitutes a pixel unit. The pixel unit may include a least one transistor (e.g., a transfer transistor [TX], a reset transistor [RX], a select transistor [SX], and/or drive transistor) according to the type of pixel unit.